The U.S. Capitol Building is one of Washington DC's most distinctive buildings. In fact, you'd be surprised how many tourists find the building so recognizable and in such a conspicuous location that they assume it must be the White House.
Capping the eastern end of the National Mall, opposite the Lincoln Memorial, the Capitol Building's distinctive dome stands as Washington DC's second tallest peak, surpassed only by the Washington Monument (by 209 feet).
Its cornerstone was laid by George Washington in 1793, but the construction to make what we see today, especially with the distinctive and massive dome, took another seventy years (with another major addition in the late 1950s with the extension of the East Portico).
The "front" of the Capitol has traditionally been the eastern side facing the Supreme Court. All presidential inaugurations from Andrew Jackson's in 1826 through Jimmy Carter's in 1977 took place on that side. But in 1981, with Ronald Reagan's inauguration, they were switched to the western side with crowds stretching back down the National Mall. In recent years the plaza on the eastern side has undergone major renovations with the addition of a new visitors' center, repaving of the entire area, and the installation of a couple of fountains.
Photos of the US Capitol Building
By far the best way to get the Capitol is by public transport--parking spots are in very short supply in the surrounding area. The nearest metro stations are Capitol South (Orange line; 0.4 miles) and Union Station (Red line; 0.7 miles).
Taking Photos at the US Capitol Building
The outside of the U.S. is generally very photography-friendly so long as you're shooting hand held (ie. not with a tripod), but there are areas where the Capitol Police and security will impose some restrictions such as on the steps or on some of the building's terraces.
There's no problem using a flash. It's entirely possible you'll get away with using a tripod, but the official policy of the US Capitol Police is:
The use of camera equipment to film or photograph on Capitol Grounds is permitted, provided the photographs or film are for private or other non-commercial use. Non-commercial documentary or historical filming is permitted on a case-by-case basis. The use of tripods or other film or photography enhancement equipment requires special permission, and it is limited to grassy areas where pedestrian or vehicular traffic will not be impeded.
The permit application form is available here [PDF]. For section 13 of that form, you'll need to enter the area numbers from this map [PDF]. And if it's approved, you'll need to be available to pick up the permit in person at the Capitol Police office at 119 D Street NE (take photo ID)--it's not just emailed to you. There's no fee for a permit for personal-use photography.
The building itself closes, but the grounds are accessible day and night. The building is brightly illuminated at night.
If you have a telephoto lens, you can get some interesting shots of the Capitol from as far away as the Iwo Jima Memorial and Arlington National Cemetery and from all the way down the National Mall. And the Capitol Reflecting Pool, (not to be confused with the larger Lincoln Memorial Reflecting Pool at the other end of the Mall).
Be aware that if you plan to go inside the Capitol Visitor Center or the Capitol Building itself there are restrictions on large bags, including large camera bags. This is from the official website:
Backpack Warning: Do not bring large daypacks, backpacks or luggage into the Capitol. Any bag larger than 14" wide x 13" high x 4" deep is prohibited.
You can find more of my photos of the US Capitol Building here.